Endless track unit



April 18, 1944. H. LAW 2,346,848

- ENDLESS TRACK UNIT I Filed Oct. 6,. 1942 2 Sheefs-Sheet. 1

INVENTOR fie rry La w 19 7'TYS Patented Apr. 18, 1944 UNITED STATES PATENT OFFICE- ENDLESS TRACK UNIT Harry Law, Merced, Calif.

Application ()ctober 6, 1942, Serial No. 460,935 8. Claims. (01. 205-4) This invention relates to endless track units for tractors and the like, of that general type in which the track links are provided with rollers which engage a rail structure on the track frame so as to guide the links about the ends of the unit independently of the link engaging sprocket wheels, and also preventing sagging of the links between the sprockets.

The main object of the invention is to provide a roller and guide rail structure so arranged and constructed that the rollers will maintain a uniform rotary speed throughout the extent of the endless track, both on the straightaways and around the end arcs, thus avoiding excessive friction and wear. Also the rollers and guide rail structure are arranged so that the pin centers of the links follow along a line between the end sprockets tangent to as well as concentric with said sprockets for the full distance therebetween before the links leave their straight line position. In this manner a maximum flat ground engaging area of the track unit is obtained.

A further object of the invention is to provide a simple and inexpensive device, and yet one which will be exceedingly effective for the purpose for which it is designed. a

These objects I accomplish by means of such structure and relative arrangement of parts as will fully appear by a perusal of the following specification and claims.

In the drawings similar characters of reference indicate corresponding parts in the several views:

Figure l is a side elevation of my improved track unit.

Figure 2 is a fragmentary enlarged longitudinal section of the same.

Figure 3 is a fragmentary sectional plan on line 3--3 of Fig. 2.

Figure 4 is a fragmentary cross section on the line 44 of Fig. 2.

Figure 5 is a plan view of a link detached.

Figure 6 is a fragmentary cross section on line 6-6 of Fig. 2.

Figure '7 is a similar viewshowing a modified form of intermediate rail.

Referring now more particularly to the characters of reference on the drawings, the track unit comprises longitudinally spaced sprocket wheels I arranged in transversely spaced pairs and turnably' supported by a suitable frame beam 2 extending therebetween and provided at its ends with bosses 3 in which the shafts 4 of the wheels are turnable. Each sprocket wheel is formed with a plurality of evenly spaced teeth 5 of round-ended form.

An endless track extends between and about the sprockets and comprises a plurality of indi vidual links, each of which includes a shoe or base plate 6 having a pair of upstanding flanges l spaced apart the same as the spacing of adjacent sprocket wheels, extending lengthwise of the shoes and end bosses 8, relatively offset laterally from each other so that the bosses on adjacent links will cooperate with each other to form the supporting members for connecting hinge pins 9. The centers of the pins are disposed justbeyond the ends of the shoes which are beveled at said ends to avoid formation of dirt pinching surfaces.

The flanges l at their ends, radially in from the bosses, are concavely curved as at I to match the curvature of the teeth 5, and so that when the links pass about the sprockets the adjacent curved ends of the flanges of the adjacent links, together, form tooth engaging sockets, as clearly shown in Fig. 1. Disposed between the flanges l centrally of the ends of each shoe is a roller l I, an axle l2supporting said roller from the flanges so that the center of the roller is radially in from the link pins 9 and the roller at its largest point clears the inner face of the shoe.

The roller is of special hour glass or spool form and has end portions I3 of a common diameter, a central portion M of a smaller diameter, and straight taper or sloping surfaces 15 connecting the portions [3 and I4.

To engage the rollers of all the track links in guiding relation, a rail unit is mounted rigid with the frame beam 2. This unit comprises transversely spaced top and bottom longitudinal rails l9 mounted directly on said beam and spaced to engage the large roller portions [3, arcuate rail members I! disposed concentric with these sprocket wheels and rotated centrally therebetween to engage the central roller por tions Id, and laterally sloping or converging rail sections 18 connecting the central members I1 and the longitudinal rails Hi.

The rails l6 terminate so that when the pins 9 of certain links are disposed in the vertical frames of the axis of the sprocket wheels, the rollers of said links will still just engage with said rails, as shown in Fig. 1; the number of links in the track being such that identical conditions are obtained at both ends as well as above and below the sprocket wheels. The rail members I! are of smaller diameter than the distance between the roller-engaging surfaces of the rails 16, and extend about the sprocket Wheels for substantially one-half the circumference thereof. This diameter relative to said distance between the rails l8 and in relation to the corresponding central and end diametral portions of the rollers is such as to compensate for the difference in linear travel of the rollers relative to that of the links themselves had when the links are passing about the sprockets, and thus gives the same rotary speed of the rollers as when the latter are running on the straight rails l6. g

The converging rail sections [8 guide and support the rollers when the latter are moving between the straight rails 16 and the arcuate rail members 11; and the roller engaging surfaces of said section 18 are so designed and laid out relative to the sloping portions l5 of the rollers as to cause said rollers to also maintain the same rotary speed while passing over the sections, as well as to cause a gradual and even movement of the links from the straight position to their sprocket engaging position. To this end the roller engaging surface of each section 18 is necessarily formed with a convex arc of large radius, as at I9, which is produced by any suitable layout method, and said surface is rounded along its outer edge as at C.

While the track sections l8 are preferably formed as separate bars or rails, they may be formed as a single rigid member as shown at l8a in Fig. 7, and whose opposed side edges converge and are rounded where they engage the sloping portions of the rollers. Also, while I have shown sprockets at both ends of the track unit, a sprocket at one end only may be used, or both sprockets eliminated when the unit is to be used as a non-driven or idling structure such as a sled.

From the foregoing description it will be readily seen that I have produced such a device as substantially fulfills the objects of the invention as set forth herein.

While this specification sets forth in detail the present and preferred construction of the device, still in practice such deviations from such detail may be resorted to as do not form a departure from the spirit of the invention, as de- A fined by the appended claims.

Having thus described my invention, what I claim as new and useful and desire'to secure by Letters Patent is: v r

1. An endless track unit comprising a supporting frame, end sprockets mounted on the frame, an endless track extending between and about the sprockets and comprisinga plurality-of individual links and pins pivoting the links together, a roller mounted on each link radially in from the pivot pins, an endless roller engaging rail unit mounted on the frame; and cooperating means formed with said rail unit and rollers to provide a constant rotary speed of the rollers throughout the length of the rail unit.

2. An endless track unit comprising a supporting frame, end sprockets mounted on the frame, an endless track extending between and about the sprockets and comprising a plurality of individual links and pins pivoting the links together, a roller mounted on each link radially in from the pivot pins, the roller having laterally spaced relatively large and small diameter portions, and a tapering portion connecting said large and small portions; and a roller-engaging rail unit mounted on the frame, said rail unit comprising a straight rail engaging the large diameter portion of the rollers of the difierent links when the latter are on the lower run of the track, an arcuate rail mounted concentric with the sprockets and engaging the small diameter portion of the rollers when the corresponding links are passing about the sprockets and a laterally sloping rail section connecting adjacent ends of the straight and arcuate rails and engaging the sloping portion of the rollers during movement of the latter between said adjacent ends of the straight and arcuate rails.

3. A structure as in claim 2, in which the roller engaging surfaces of the rails and rail section are so formed and related to each other and to the size of the corresponding engaging surfaces of the rollers as to cause the rollers to turn at the same speed throughout the length of the rail unit.

4. A structure as in claim 2, in which each roller is disposed centrally of the length of the corresponding link and the first named rail terminates substantially in the vertical planes of the axes of the sprockets.

5. In an endless track structure which includes an end sprocket wheel having teeth and an endless track extending the length of the structure and about the sprocket wheel, said track including. a plurality of shoes pivoted together; a flange extending lengthwise of and projecting radially in from each shoe in the plane of the sprocket wheel transversely of the track structure, each flange being concaved at its ends symmetric to one side of the teeth and arranged so that adjacent ends of adjacent flanges, when the track is passing about the sprocket wheel, form tooth engaging sockets.

6. In an endless track structure which includes an end sprocket wheel having teeth and an endless track extending the length of the structure and about the sprocket wheel; said track including a plurality of shoes pivoted together; elements on and projecting radially in from each shoe, the elements of adjacent shoes, when the track is passing about the sprocket wheel, being disposed and arranged to form tooth engaging sockets, rollers mounted on the shoes and a fixed guide rail unit for the rollers extending about the sprocket wheel whereby to maintain the track in clearance and non-binding relation to the sprocket wheel in a radial direction.

7. An endless track unit including a supporting frame, an endless track arranged in connection with the frame and comprising a plurality of individual links, pins pivoting the links together and a roller mounted on each link radially in from the line of the pivot pins; an endless roller engaging and track supporting rail unit mounted on the frame and including arcuate end portions and longitudinal top and bottom portions, and cooperating means formed with said rail unit and rollers to provide the same rotary speed of the rollers about the arcuate portions as along said longitudinal portions of said rail unit.

8. An endless track unit including a supporting frame, an endless track arranged in connection with the frame and comprising a plurality of individual links, pins pivoting the links together and a roller mounted on each link radially in from the line of the pivot pins; an endless roller engaging and track supporting rail unit mounted on the frame radially inward of the axial line of the rollers and cooperating means formed with the rail unit and rollers to provide a constant rotary speed of the rollers throughout the length of the roller unit.

HARRY LAW. 

